Arrests come as Harare high court set to announce ruling on election results.

Results for parliamentary polls held on the same day trickled out and gave the opposition Movement for Democratic Change (MDC) the majority of seats.

The hearing, which was postponed from Monday, is due to start at 1000 GMT.

The MDC, led by Morgan Tsvangirai, claims it also won last week's presidential election, but Mugabe's Zanu-PF party, said there was no clear winner and has called for a run-off vote.

Supa Mandiwanzira, Al Jazeera's correspondent in Harare, the capital, said the election commission originally argued that the case could not be brought before the high court because it had no jurisdiction over a constitutional body.

However, Justice Tendai Uchena announced on Monday that contrary to the assertions of the commission, whose leaders are appointed by Mugabe, his court did have jurisdiction to hear the case.

International appeal

Tsvangirai travelled to South Africa on Monday to meet Jacob Zuma, president of the country's governing African National Congress (ANC), in order to encourage South Africa to act with the UK and the US "to remove the white-knuckle grip" of 84-year-old Mugabe.

Although Zuma has no formal position in the South African government, he is the frontrunner to succeed Thabo Mbeki as president, and his role as ANC leader gives him influence in the development of the party's domestic and foreign policies.

Zuma had criticised Mbeki's policy of "quiet diplomacy" towards Zimbabwe until his election to lead the ANC, when he voiced support for that policy.

In a commentary in Monday's issue of British newspaper, The Guardian, Tsvangirai wrote: "A mooted presidential run-off ... is a sham.

"Our country is on a razor's edge."

Tsvangirai has since urged the International Monetary Fund (IMF) to withhold £1bn in aid to Zimbabwe unless Mugabe "accepts the election results".

Unity snub

Tsvangirai's opposition party seized parliamentary control from Zanu-PF for the first time in legislative elections, but Mugabe's ruling party is contesting enough seats to reverse that result.

Tsvangirai has made his first trip outside the country since the election[AFP]

On Sunday, state media reported that Zanu-PF snubbed an approach from the MDC to form a unity government, but the MDC denied that a unity government was ever on the table.

Also on Sunday, supporters of Mugabe forced about a dozen white ranchers and farmers off their land as Zimbabwe's longtime ruler fanned racial tensions amid fears he will turn to violence to hold on to power.

"This is our soil and the soil must never go back to the whites," Mugabe said on Sunday, referring to whites by the Shona term "mabhunu," the Zimbabwean Herald reported.

Mike Clark, spokesman for the Commercial Farmers Union, said at least 23 farms were invaded and the owners of about half of them were driven off their land.

He said the farms were in at least seven areas across the country, saying land grabs had "become a national exercise".

Police in some areas persuaded the intruders to leave, but elsewhere officers did not intervene, saying it was a political matter, Clark said.

Mugabe has ruled Zimbabwe without interruption since the country gained independence from Britain in 1980. His support, however, has slipped amid a severe economic crisis.

Zimbabwe has the world's highest rate of inflation - more than 100,000 per cent - and about 80 per cent of the work force is without employment.